Molecular analysis of the hrp gene cluster in Xanthomonas oryzae pathovar oryzae KACC10859

Cho, Hee-Jung; Park, Youngjin; Noh, Tae-Hwan; Kim, Yeong-Tae; Kim, Jeong-Gu; Song, Eun-Sung; Lee, Dong-Hee; Lee, Byoung-Moo

doi:10.1016/j.micpath.2007.12.002

Cited by 43 publications

(47 citation statements)

References 24 publications

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“…oryzicola does not render the pathogen unable to trigger the HR in nonhost tobacco (unpublished data), in contrast to that in X. oryzae pv. oryzae (9), suggesting that there are more than two harpins in Xanthomonas species. (iv) Hpa1 is secreted via the T3SS in an HpaB-independent manner (our unpublished data) similar to that of its homolog XopA in X. campestris pv.…”

Section: Discussionmentioning

confidence: 99%

“…However, hrpF mutation has not been investigated in X. oryzae pv. oryzicola.The hpa genes contribute to virulence, but strains with mutations in hpa genes generally do not exhibit phenotypic changes in disease symptoms of the same severity as those with other hrp-hrc gene mutations (9,25,29). Some Hpa proteins, such as HpaB and HpaC from Xanthomonas campestris pv.…”

mentioning

confidence: 99%

“…oryzicola, the causative agent of bacterial leaf streak disease in rice, is one of the model organisms for studying the molecular mechanisms of plant-pathogen pathosystems (41, 59). The bacterial ability to trigger the hypersensitive response (HR), a rapid and localized programmed cell death in nonhosts or in resistant hosts, and to be pathogenic in host plants depends on a type III secretion system (T3SS) encoded by a 27-kb hrp cluster containing 10 hrp, 9 hrc (hrp-conserved), and 8 hpa (hrp-associated) genes according to the homologous regions in other Xanthomonas species (9,41,59). Some of the hrp-hrc-hpa gene products comprise a pedestal-like T3SS structure that traverses the two bacterial membranes (21, 24), a pilus-like secretion channel (HrpE) outside HrcC (52), and a translocon protein (HrpF) in the eukaryotic host membrane (3, 4, 6, 21, 48).…”

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confidence: 99%

“…In X. oryzae pv. oryzae, diverse phenotypes displayed in rice by hpa gene mutants suggest that Hpa proteins have distinct individual functions (9).…”

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confidence: 99%

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Hpa2 Required by HrpF To Translocate Xanthomonas oryzae Transcriptional Activator-Like Effectors into Rice for Pathogenicity

Che

Zou³

et al. 2011

Appl Environ Microbiol

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Xanthomonas oryzae pv. oryzicola, the causative agent of bacterial leaf streak, injects a plethora of effectors through the type III secretion system (T3SS) into rice cells to cause disease. The T3SS, encoded by the hrp genes, is essential for the pathogen to elicit the hypersensitive response (HR) in nonhost tobacco and for pathogenicity in host rice. Whether or not a putative lytic transglycosylase, Hpa2, interacts with a translocon protein, HrpF, to facilitate bacterial pathogenicity remains unknown. Here we demonstrated that both the hpa2 and hrpF genes are required for the pathogenicity of X. oryzae pv. oryzicola strain RS105 in rice but not for HR induction in tobacco. The expression of hpa2 was positively regulated by HrpG and HrpD6 but not by HrpX. In vivo secretion and subcellular localization analyses confirmed that Hpa2 secretion is dependent on HpaB (a T3SS exit protein) and that Hpa2 binds to the host cell membrane. Protein-protein assays demonstrated that Hpa2 interacts with HrpF. In planta translocation of AvrXa10 indicated that the mutation in hpa2 and hrpF inhibits the injection of the HpaB-dependent transcriptional activator-like (TAL) effector into rice. These findings suggest that Hpa2 and HrpF form a complex to translocate T3S effectors into plant cells for pathogenesis in host rice.Xanthomonas oryzae pv. oryzicola, the causative agent of bacterial leaf streak disease in rice, is one of the model organisms for studying the molecular mechanisms of plant-pathogen pathosystems (41, 59). The bacterial ability to trigger the hypersensitive response (HR), a rapid and localized programmed cell death in nonhosts or in resistant hosts, and to be pathogenic in host plants depends on a type III secretion system (T3SS) encoded by a 27-kb hrp cluster containing 10 hrp, 9 hrc (hrp-conserved), and 8 hpa (hrp-associated) genes according to the homologous regions in other Xanthomonas species (9,41,59). Some of the hrp-hrc-hpa gene products comprise a pedestal-like T3SS structure that traverses the two bacterial membranes (21, 24), a pilus-like secretion channel (HrpE) outside HrcC (52), and a translocon protein (HrpF) in the eukaryotic host membrane (3, 4, 6, 21, 48). As a whole, the T3SS apparatus injects a number of effectors into the apoplast and cytosol of eukaryotic host cells, including harpins, which elicit HR induction in nonhost apoplasts (4, 45, 58), and transcriptional activator-like (TAL) effectors, which lead to disease susceptibility in hosts or trigger disease resistance in nonhosts upon interaction with a specific R gene product surveillance system (4,11,38,39,40,49,56). The virulence of Xanthomonas oryzae pv. oryzae is markedly reduced when hrpF is mutated (48). However, hrpF mutation has not been investigated in X. oryzae pv. oryzicola.The hpa genes contribute to virulence, but strains with mutations in hpa genes generally do not exhibit phenotypic changes in disease symptoms of the same severity as those with other hrp-hrc gene mutations (9,25,29). Some Hpa proteins, such as HpaB and HpaC ...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…In X. oryzae pv. oryzae, diverse phenotypes displayed in rice by hpa gene mutants suggest that Hpa proteins have distinct individual functions (9).…”

mentioning

confidence: 99%

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Hpa2 Required by HrpF To Translocate Xanthomonas oryzae Transcriptional Activator-Like Effectors into Rice for Pathogenicity

Che

Zou³

et al. 2011

Appl Environ Microbiol

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“…BLB is a vascular disease in which X. oryzae pv. oryzae grows and colonizes the xylem vessels, eventually clogging them; several virulence-associated determinants have been found, including exopolysaccharide production, hypersensitive response, and pathogenicity (hrp) genes (7,20,26).…”

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confidence: 99%

OryR Is a LuxR-Family Protein Involved in Interkingdom Signaling between PathogenicXanthomonas oryzaepv. oryzae and Rice

2009

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Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated OryR, which belongs to the N-acyl homoserine lactone (AHL)-dependent quorum-sensing LuxR subfamily of proteins. However, we previously reported that X. oryzae pv. oryzae does not make AHLs and does not possess a LuxI-family AHL synthase and that the OryR protein is solubilized by a compound present in rice. In this study we obtained further evidence that OryR interacts with a rice signal molecule (RSM) and that the OryR concentration increases when rice is infected with X. oryzae pv. oryzae. We also describe three OryR target promoters which are regulated differently: (i) the neighboring proline iminopeptidase (pip) virulence gene, which is positively regulated by OryR in the presence of the RSM; (ii) the oryR promoter, which is negatively autoregulated independent of the RSM; and (iii) the 1,4-␤-cellobiosidase cbsA gene, which is positively regulated by OryR independent of the RSM. We also found that the RSM for OryR is small, is not related to AHLs, and is not able to activate the broad-range AHL biosensor Agrobacterium tumefaciens NT1(pZLQR). Furthermore, OryR does not regulate production of the quorum-sensing diffusible signal factor present in the genus Xanthomonas. Therefore, OryR has unique features and is an important regulator involved in interkingdom communication between the host and the pathogen.The species Xanthomonas oryzae includes two pathovars, X. oryzae pv. oryzae and X. oryzae pv. oryzicola, which are pathogens of rice, are closely related, and were initially considered pathovars of Xanthomonas campestris (28). X. oryzae pv. oryzae is a gram-negative rod-shaped bacterium that causes bacterial leaf blight (BLB), one of the most important diseases of rice.

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Microbial Protein Elicitors in Plant Defense

Joshi

Senthamilselvi

Maupin-Furlow

et al. 2022

Microbial Biocontrol: Sustainable Agriculture and Phytopathogen Management

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Molecular analysis of the hrp gene cluster in Xanthomonas oryzae pathovar oryzae KACC10859

Cited by 43 publications

References 24 publications

Hpa2 Required by HrpF To Translocate Xanthomonas oryzae Transcriptional Activator-Like Effectors into Rice for Pathogenicity

Hpa2 Required by HrpF To Translocate Xanthomonas oryzae Transcriptional Activator-Like Effectors into Rice for Pathogenicity

OryR Is a LuxR-Family Protein Involved in Interkingdom Signaling between PathogenicXanthomonas oryzaepv. oryzae and Rice

Microbial Protein Elicitors in Plant Defense

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